1. Field of the Invention
The present invention relates to a generating device of trigger signal which generates a trigger signal so as to shift the state of an appliance by receiving a radio signal.
2. Description of the Related Art
Such an electrical appliance as a television set can be generally switched on and off with the corresponding remote control. An optical signal emitted from the remote control is received at the electrical appliance so that the electrical appliance is switched on. In order to realize the operation of the switch-on of the electrical appliance, the optical receiver and the electrical power controller in the electrical appliance are always set operable. Namely, even though the electrical appliance is not switched on, some electrical power is always consumed because the optical receiver and the electrical power controller are set operable.
As described above, the remote control uses an optical signal. Since the remote control using the optical signal can be manufactured at low cost, the remote control can not perform the optical communication if an obstacle is located between the remote control and the electrical appliance. In this point of view, such a receiving structure as an RFID tag which utilizes an electromagnetic wave is proposed (refer to Reference 1). In Reference 1, in order to reduce the electric power consumption of the electrical appliance at the standby state thereof, a starting switch is inserted between the rectifier of the RFID tag and the electrical appliance. A power source is provided for the starting switch from the electrical appliance and no power source is provided for the rectifier.
The power source for the electrical appliance is controlled in on-off on the basis of the output state of the starting switch. When the starting switch outputs an off signal, the electrical appliance is switched off so that the electric appliance does not consume the electric power. When the staring switch outputs a signal, the electrical appliance is switched on. For example, with a television set, some images are displayed on the screen and some voices and sounds are created. The power source is provided for the starting switch from the electrical appliance, and the power source may be made from a CMOS inverter. In this case, no electrical current is supplied for the starting switch because the nMOS transistor or pMOS transistor of the inverter is set off irrespective of the operation state of the inverter.
The rectifier receives an external electromagnetic wave with the antenna and then, generates the electric voltage through the electric power originated from the electromagnetic wave. The output voltage of the rectifier becomes large as the input electric power into the rectifier becomes large. Since no electric power is supplied to the rectifier from the electric appliance, the standby electric power of the rectifier becomes zero. By inputting the output voltage of the rectifier into the starting switch, the on-off control signal for the electrical appliance can be generated. As a result, the electric power consumption at standby state of the remote control with the inverter as the power source can be reduced in comparison with the remote controller with the optical signal.
However, since the rectifier can generate a smaller electric voltage through the input of the electric power originated from the electromagnetic wave, the starting switch can not be switched on and off only if a larger electric power is input into the starting switch from the rectifier. Namely, it is required to apply a larger electric power to the RFID tag so that the distance between the electric appliance and the remote control can not be enlarged.
It is proposed in References 2 and 3 to render the electric power to be generated from the rectifier large. According to the improved rectifier disclosed in References 2 and 3, therefore, the operable distance of the remote control can be enlarged to some degrees.
[Reference 1] JP-A 2001-197537 (KOKAI)
[Reference 2] JP-A 2006-034085 (KOKAI)
[Reference 3] JP-A 2006-166415 (KOKAI)